Iontophoresis refers to a technique for making a micro current flow into the skin and making a material of interest having charges pass into the skin through electrical repulsive force. An iontophoresis patch is used for passing a material of interest, such as a medicine or a cosmetic material, through the skin by using electrical repulsive force. When a patch coated with a material of interest is attached to the skin, a circuit is formed and a current flows, and the material of interest passes into the skin by the electrical repulsive force. It is known that a speed of passing the material of interest is directly affected by a quantity of current flowing into the skin.
A conventional iontophoresis patch is manufactured by a method of independently manufacturing a thin film battery and a patch or a pad including electrically conductive electrodes and then electrically connecting and assembling the electrically conductive electrodes with the thin film battery. The iontophoresis patch manufactured by the aforementioned method has problems of the increase of the current resistance due to a complex current flow route, and low productivity and high manufacturing costs resulting from a complex assembling procedure.
The battery mounted on the iontophoresis patch functions as an energy resource for generating a current, and generally includes two electrodes serving as a positive electrode and a negative electrode and an ion conductive electrolyte. In general, manganese dioxide is used as a material of the positive electrode and zinc is used as a material of the negative electrode, and a gel-type electrolyte, in which zinc chloride or ammonium chloride is dissolved in water together with polymers, is induced into the battery. When binders within the electrodes are dissolved in an aqueous electrolyte during the distribution of the battery after the manufacturing, it results in a short together with the increase of the resistance, thereby sharply deteriorating the performance of the battery. Especially, when it fails to secure the durability of the electrodes against the aqueous electrolyte in a case when the positive electrode is located adjacent to the negative electrode without an isolation film therebetween, a conductive material within the electrodes is separated, so that it serves as a current crosslink with respect to an opposite electrode and thus the short phenomenon is easily generated. In order to overcome the drawback, the electrode, especially the negative electrode, has inevitably employed zinc shaped like a foil or a strip as the material of the electrode. However, if the metal foil is employed as an electrode active material, a reaction area is decreased compared to the electrode manufactured in a powder state, so that a high power property is weak and the productivity is easily decreased.
In order to solve the problems, especially low productivity and the high electrical resistance, Patent Application No. 2007-99132 entitled “Iontophoresis patch and Method of Manufacturing the same” previously filed by the applicant of the present invention discloses the construction in which a patch and a battery are configured as one system by directly coating a material of electrodes on a conductive layer within the patch, which was conceived so as to reduce a contact resistance against the skin. The patch having the aforementioned construction has a structure advantageous to increase the passing of a material of interest into the skin according to a simple current mechanism and a small resistance. However, the patch has a problem in that a material of interest having a weak electrochemical tolerance involves the battery reaction. Further, it is necessary to further simplify a patch manufacturing process and further secure a flexibility of the patch.
As noted from the above description, a lower productivity, high manufacturing costs, a performance deterioration resulting from the electrode structure destruction during the distribution, etc. are now obstacles to the commercialization of the iontophoresis patch. Accordingly, a technical approach is necessary in order to effectively solve the aforementioned problems of the existing iontophoresis patch.
An electric and electronic device consuming a micro current, as well as the iontophoresis patch, may use a thin film battery as a power resource. For example, the thin film battery may be used for devices including a Radio Frequency Identification (RFID) tag, a smart card, and an electronic paper display. In the device having the thin film battery, it is necessary to further decrease manufacturing costs through the reduction of the number of manufacturing processes, further improve the flexibility of the device, and stably supply a power to the thin film battery.